Mounting of grinding wheels, especially on grinding machines



E. BUGATTI Oct, 19, 1948.

' MOUNTING 0F GRINDING WHEELS, ESPECIALLY ON GRINDING IACHINES FiledSept. 11, 19 45 2 Shoots-Shut 1 m m h H a 3 S a a I up 5 .7 g *1 m .3 vWe W H .Q a a, i I 3 Q a $2 2 Q 4 N k 4 a" N R my m NW N m av a x 51 a EI N N N. k a

Patented Oct. 19, 1948 UNITED srATEs {P AT ai NT oFFics-Application-September 11, 1945, SerIal No. 815.63

In France December 3, 1943 Section "1, Public Law L690, Augustll, 194slfatent December 3. 1983 1 15 Claims. (01. ti-166i It is known that thegrinding wheel-spindle a grinding machine is one of the most delicateparts of machines of this kind. As a matter of fact they must, on theone hand, allow fast rotation of grinding wheels sometimes very heavyand diflicult to equilibrate, on the other hand, receive motion from oneorseveral pulleys, counterbalancing of which is also defective.

- Expansion phenomena complicate the designing thereof owing to the factthat they compel to provide particular compensating devices, the use ofwhich does not always 'suillce to avoid play when the spindle and itsbearings are cold;

, These various considerations have led constructors to take manyprecautions with a view to 5. The resilient couplings connected to theinner driving spindle may slide, one in a bore of the driving pulley,the other in a similar housing arranged; in that part of the grindingwheel shaft I which, faces the grinding wheel. Moreover, these resilientcouplings are fast'with' the driving spindle in axial direction. Twoequal coil-springs or two sets of equal, concentrically arranged springshold the driving spindle and its couplings in axial securing a constantaccuracy consonant with that of the whole machine, and as .far aspossible to eliminating vibrations which aredetrin ental to finish ofmachined work. Originally, grinding wheels are equilibrated togetherwith the spindles bearing them, pulleys and even belts but in operationthese precautions are not always observed. i when one or several memberssuch as grinding wheel or belts are rep1aced,.thus making illusive theadvantages to be expected from the original mounting of spindles.

A primary object of this invention is to do away with the drawbacksabove mentioned; In a preor,the like, one of the stationary-rings ofwhich i direction and allow of length variations of the grinding wheelshaft and driving pulley.

6. The bearing for'the grinding wheel shaft' may be lubricated withpressure lubricant. Feeding of lubricant is made preferably through the'upper part of the bearing, and oil escaping from the ends of the latteris collected in cavities arranged for this purpose and provided, if needbe, with deflectors, from where it comes back to a main container in theframe, through a series of suitable passages in the lower part of thebearing.

7. In order to prevent access of dust and fillings to the bearing a setof bailles is provided on the 1 side of the grinding wheel, stationarymembers rests against the shaft hearing or a member fast with thelatter, through a set of coil-springs arranged on one or severalconcentrical r0ws.- This manner of mounting allows of axial expansion ofthe grinding wheel shaft and precludes any axial play of the grindingwheel shaft in its bearing.

3. Drive is conveyed to the grinding wheel by means of a spindle havinga weak inertia and turning inside the grinding wheel shaft. Said drivingspindle is actuated, at an end, by means of a pulley, through aresilient coupling and at the other end, it drives the grindin wheelshaft through another resilient coupling, 4

4. The drivin pulley, above mentioned under 3, is provided withball-bearings or with cylindrical or conical roller bearings which arelooked through their inner rings, on a stationary member appended to thebearing of the grinding wheel shaft.

of said baffles belonging to the bearing while the rotating membersbelon .to thegrinding wheel shaft; furthermore one or several feltpackings are arranged to rub on the grinding wheel shaft. For protectingthe ball or roller bearings of the driving pulley, deflectors fast withsaid pulley are provided;

8. The bearing of thegrinding wheel shaft has, preferably, a cylindricalshape as also its extension which supports the driving pulley. Thispulley and that part of the extension located between said pulley andhearing may be slightly smaller than the bearing, so that the latter maybe placed on a cradle of any length.

9. The bearing of the grinding wheel shaft is, preferably, secured inits cradle by means of straps, the threaded lugs of which are longenough to enable locking of nuts with interposi- "tion of a set ofBelleville washers or coil-springs.

From examination of the features above recited, it results that grindingwheel shafts constructed accordin to my invention secure the followingadvantages:

1. The grinding wheel shaft is sheltered against any consequence arisingfrom a possible defect of counterbalancing of the driving pulley andhence is not subjectedto trepidations and vibrations from said pulleyand its belts. Said grinding wheel shaft may be separately balanced,with the grinding wheel on it, without taking into consideration theother turning masses.

2. Torsional vibrations arising from the disturbances above mentionedare absorbed by the in its bearing can occur; the springs, housed in thebearing between the latter and one of the rings of the double-acting--ball thrust bearing,

continually press the three rings of the latter against the stationarypart. Any adjustment of axial play of. this ball thrust bearing, such anadjustment being always very difficult to perform, is therefore avoided.n the other hand, in the case where the grinding wheel unexpectedlycomes into contact with the work or a foreign body, said springs act asa damper and allow in some degree, of .avoiding deterioration of thegrinding wheel or'itssh-aft.

4. In the same order of ideas, the resilient fastening of the bearing onthe machine frame completes the various provisions made to diminish theconsequences-of any possible wrong operation.

5. Lubrication under pressure, which may easily be adapted to thebearing of the grinding wheel shaft, allows of continually driving outdusts and filings whichtend to infiltrate through tightness felts. .Thebaffles provided near the grinding wheel hub co-operate to thissheltering.

I explained, the application of roller or like bear- 6. As the drivingpulley is wholly independent of the grinding wheel shaft, it can beequilibrated separately once for all, this being much easier thanequilibrating a combination comprising the grinding wheel, shaft andpulley. Further, it will be remarked that when the grinding wheel ischanged its shaft alone is concerned; the driving part proper (pulleyand belts) keeps its own balancing.

The following description withreference tothe appended drawings givensolely by way of example will show how this invention may be carriedout.

wheel shaft carried out according to this invention.

Fig. 2 is a cross-section taken along line 11-11 'on Fig. 1.

stationary ring 5 iscentered in a recess of side 8, j

whilethe other stationary ring 5 may slide in a bore 9 in bearing 3. Aset of coil-springs Ill located in holes provided in that portion ofbearing 3 which extends radially and inwardly so as to provide in effectan abutment member, keep the various members of the ball thrust bearingin mutual Contact. This set of springs It! may be completed by a set ofless strong springsi0,- acting in opposition and having merely for itsfunction to hold against one another, the member 1 and 8 of the ballthrust bearing. The rotary ring-6 is pressed against a shoulder on thegrinding wheel shaft I by means of a nut H screwed ona threaded part l2of the shaft I, which extends beyond said shoulder.

The driving pulley 4,-actuated by means of belts l3 which convey drivefrom an electric motor or any shaft dependent on the machine, turns onball-bearings I4 and I4. As above Fig. 1 shows, in longitudinal section,a grinding ings is also possible.

Ball-bearings l4 and W are located in a bore l5 of the pulley4, which isopen so as to allow of piling up ball bearings l4 and l4'. A threadedring l6 which acts at the same'time as an oil deflector, holds,- byresting on a shoulder ll of the pulley 4, the outer ring of ball-bearingN" on the right of Fig.1, while the other ball-bearmg l4, has its outerring in abutment on the bottom' of bore l5.

Inthis zone, pulley 4 has an oil deflector l8, which, for the best, isintegral with said pulley 4. The inner rings of ball-bearings I4 and Ware pressed against a shoulder of bearing 3, with an intervening spacer49, by a nut 2|] screwed on a threaded part 2| of bearing 3. Nut 26 islocked by-a steel wire brake 22.

Pulley 4 has-further ahousing 23 in which is mounted with an easy fitthe outer ring 24 of a resilient coupling 25- which conveys drive to aspindle 26 through its inner ring ,21 and'a plastic mass 28. Theresilient coupling 25 may bemade in any known manner, and driven forinstance,

either through alternating projections on its outer' said adherencebeing obtained by vulcanization or any other manner..

The outer ring 24 is provided with one or several keys 29 slidablyengagingsuitable grooves 30 in pulley 4. The inner ring 21 has also oneor several keys 3| slidably mounted therein and which are embedded inspindle 26; ring 21 is abutted against a, shoulder onspindle 26 by anut'32 screwed on a threaded part 33 of spindle 26.

An annular plate 34, secured on pulley 4 by means of a set of screws 35,limits axial displacements of'spindle 26 and its coupling 25.- A plasticring 36 may be-inserted between ring 21 of coupling 25 and annular plate34, so as to make up for clearance between these members and avoidingress of dust into bore 23.

A coil-spring 3'l confined between the threaded ring l6 turning withpulley 4 and a dished plate 38 which rests against the ring 21 ofcoupling 25, axially pushes the spindle 26 in opposition to pressure ofa spring 39 which acts on the other end of spindle 26.

- Said spring 39 rests on a side 40 of the grinding wheel shaft l and onthe inner ring 2! of a resilient coupling 25' which conveys drive fromspindle 26 to grinding wheel shaft I. The resilient coupling 25' ismounted in like manner to coupling 25. Its outer ring 24 is adapted toslide in a recess 4| of grinding wheel shaft I the aforesaid side 40constituting-the bottom of said recess. Two keys 42 and 43, the firstone 42 engaging shaft 26 and ring 21', while the other 43 engages ring24' and slides in a groove 44 of recess 4|, cooperate to drivetransmission between shaft 26 and grinding wheel shaft l.

The hub 46 of grinding wheel 41 is locked by a threaded ring 45, and isfor the best, provided with a female cone 48 engaged by the male cone 49on grinding wheel shaft I. A plastic ring 50 acts as a dust excluder,like rin 36 provided at the other end of the shaft between annular plate34' and ring 24. Nevertheless, the dimensions of the plastic ring 50have been calculated more broadly than those of ring 36, in order toafford a greater capacity for compression and, therefore, to fill inmore certainly the gap between nut and ring 24. e

In order to complete the description, I shall mention a nut 5| screwedon a threaded part 46 of the hub 46, and a grinding wheel casing 52attached in any manner on the bearing 2 of the grinding wheel shaft. v

Lubricating oil from a pump is supplied to bearing 2 through a piping 53ended by a union 54 screwing into a tapered hole 55 in bearing 2. Thehole 55 opens through its lower part into a longitudinal or helicalgroove 58 in the. bore of bearing 2, for the purpose of distributingoil. The excess oil which goes out of the bearing on the side of thegrinding wheel is projected towards the periphery of a space 51 by adeflector 5 8 which is shrunk on grinding wheel shaftl or is integraltherewith. The space 51 has, at its lower part, a well 59 in which opensa bore 60 drilled in the body of bearing 2. A cover 6!, made of twoparts with a view to allowing mounting, provide walls for the space 51;this cover cooperates by ribs 62 with shaft I also provided with similarribs 63, so as to form bafliing means between the stationary and turningmembers. A felt packing 64, located in a groove of cover 6i, precludesoil infiltrations which might happen when stopping. 'Cover BI is securedon hearing 2 by a set of studs 65 and nuts 66.

On the side remote from the grinding wheel, a space 61 provided in shafti and in which opens a bore 68, and likewise a space 69 in bearing 3secure return of oil towards a lower opening which communicates with theoil container of the machine through a suitable piping.

Fig. 2 shows the arrangement of springs l0 and oil return space 69, andFig. 3 the fastening device of bearing 2 on its crade II. A strap 12 isunited by riveting with lugs 13 which have a smooth part, long enough toallow of a set of Bellevllle washers by means of nuts 14. Instead ofBelleville washers very strong springs, or even rubber blocks or blocksof any other plastic material may be used.

It will be obvious that minor alterations may be brought about in theforegoing embodiments without departing from the spirit of the appendedclaims.

What I claim is:

1. In a grinding machine, a grinding wheel supporting and driving unithaving a cylindrical outer shapesubstantially throughout its length,which comprises three successive cylinder sections, one of which is abearing having a bore, the

following one is a tubular extension which has a tubular extension. forcoupling the pulley .withthe shaft. I

2. The combination of claim 1', which further comprises resilient meanslocated in the bore of the tubular extension, interposed between theshaft and said extension for resisting axial movement of said shaft inthe direction of the abovenamed sequence of cylinder sections.

3. The combination of claim 1, the bearing having a lubricant inlet portextending to its bore,

, a lubricant outlet port opening on the outer surface of the bearing,and intermediate lubricant return channels from the ends of said bearingto said outlet port, the combination furthercomv 6 prising meansattached to said hearing at its end remote from the tubular extensionproviding a seal around said shaft. 4. The combination of claim 1,further comprising. a frame having a recess in the form of a cylinderportion, adapted partially to accommodate said unit; and resilientflexible means providing a strap over the exposed portion of the unitpositioned in said recess for holding said unit in the recess. 5. In agrinding machine, thecombination of a bearing having a length which isconsiderable with respect to the diameter of the bore of said bearing;a, grinding unit .including a grinding wheel and a tubular wheel shaftwhich is located on one side of said grinding wheel, and which is fastwith said wheel, and is revolubly borne in said bearing; wheel drivingmeans rotatably supported from said bearing at the end thereof which isremote from said grinding wheel; a spindle accommodated in said tubularwheel shaft, extending from a, point in the plane of the grinding wheelto a point in the plane of the wheel driving means; means in the planeof said grinding wheel for resiliently coupling said shaft with saidgrinding unit; and resilient means in the plane of said wheel drivingmeans, for coupling said wheel driving means with said shaft. 6. In agrinding machine, the combination of a main bearing which has aconsiderable length as compared with the diameter of its bore, andcomprises an inner peripheral recess in its bore and an outer peripheralrecess, said recesses being in spaced apart relationship at an end ofsaid bearing;- a grinding unit including a grinding wheel and a tubularshaft fast with said wheel, located on one side thereof and revolublyborne in said main bearing, said grinding wheel being located at the endof said main bearing which is remote from the first-named end thereof;means in said inner peripheral recess, adapted and arranged to cooperatewith said tubular shaft, providing athrust bearing for said shaft; meansrevolubly borne on the main bearing in the outer peripheral recessthereof, for driving said grinding wheel; and means extending throughsaid tubular shaft for-transmitting drive from said driving means tosaid grinding unit.

7. The combination of claim 6, which further comprises resilient meansin said inner peripheral recess, backed from said main bearing, forurging said thrust bearing towards the secondnamed endof the mainbearing.

8. In a grinding machine, the combination of a main bearing which has aconsiderable length as compared with the diameter of its bore and has anouter peripheral recess and an inner peripheral recess having axiallyspaced apart, radial walls, each of which has at least one axiallydirected hole, said recesses being disposed in spaced apart relationshipat an end of the main bearing; a grinding unit including a. grindingwheel and a tubular shaft fast with said wheel, located on one sidethereof and revolubly borne in said main bearing, said grinding wheelbeing located at the end of the main bearing which is remote from thefirst-named end thereof; an antifriction thrust bearing for said tubularshaft, adapted and arranged to cooperate therewith, supported and guidedin said inner peripheral recess of the main bearing for axial movementtherein, said thrust bearing having an axial extent less than thedistance between the radial walls of said inner recess; a spring nestedin each of said axially directed holes, adapted and arranged to be com-7 pressed between said main bearing and said thrust bearing, the springlocated on the side proximate to the first-named end of the main bearingbeing weaker than the spring on the other side; means revolubly borne onthe main bearing in the outer peripheral recess thereof} for drivingsaid grinding wheel; and means extending through said tubular shaft fortransmit ting drive from said driving means to said grinding unit.

9. In a grinding machine, the combination of wheel; a spindle in saidtubular shaft, co-extensive with said shaft and said wheel drivingmeans,

said spindle being adapted and arranged at the end thereof adjacent tosaid grinding wheel for axially movable, driving engagement with thegrinding unit, in the plane of the wheel, said spindle being alsoadapted and arranged at the end thereof remote from said grinding wheelfor axially movable, driving engagement with said wheel driving means;and a, pair of resilient means operatively interposed between saidspindle and said grinding unit, and between said spindle and said wheeldriving means respectively, adapted to urge the spindle in axiallyopposite directions, for biassing said spindle to operative engagementwith said grinding unit and wheel driving means.

10. In a grinding machine, the combination of a frame including anelongated cradle portion and at least two longitudinally spaced apartlugs 'on each side of said cradle portion; a grinding unit including along bearing for a grinding wheel shaft and for means to drive saidshaft, said long bearing being so shaped as to seat in said cradle; atleast two flexible straps, each of which extends from a lug on one sideof said cradle to the opposite lug on the other side of said cradle; andmeans providing an adjustable, resilient connection between each. lugand the corresponding strap. 1

11. In a grinding machine, the combination of a bearing; a grindingwheel shaft having a grinding wheel at an end thereof, rotatably bornein said bearing, said shaft having its opposite end which protrudes fromthe corresponding end of said bearing; a ring on said opposite end ofsaid shaft, fast therewith so as to be rotatable with said shaft; aradially extending, abutment member around said opposite end of saidshaft, axially spaced apart from said rotatable ring and positioned withrespect to the latter on the side thereof remote from said bearing;rigid means for supporting said abutment member from said.

bearing; and resilient means operatively interposed between saidrotatable ring and abutment member for resisting axial thrusts imposedon said shaft in the direction from the first-named end of said shaft tosaid opposite end thereof, said resilient means being predetermined tobe operative only with abnormal axial thrusts.

12. In a grinding machine, the combination of a bearing; a grindingwheel shaft having a grinding wheel at an end thereof, rotatably bornein said bearing, said shaft having its opposite end which protrudes fromthe corresponding end of said bearing; a ball thrust bearing having one.8 of its two rings secured in radial position on said opposite end ofsaid shaft, the remainder of said ball thrust bearing being located onthe side of said ring remote from said shaft bearing; a radiallyextending, abutment member around said opposite end of i said shaft,located on the same side as, but farther from said shaft hearing than,said ball thrust bearing; rigid means for supporting said abutmentmember from said bearing; and resilient means in prestressed conditioninterposed between said abutment member andthe second ring of said ballthrust hearing, for urging said ball thrust bearing towards said firstnamed end of said shaft bearing.

13. In a, grinding machine, the combination of a bearing; a grindingwheel shaft having a grinding wheel at an end thereof, rotatabiy bornein said bearing, said shaft having its opposite end which protrudes fromthe corresponding end of said bearing; a tubular extension removablysecured to said bearing at the opposite named end thereof, coaxiallytherewith, said tubular extension having such an inner diameter as toleave an annular, unobstructed space between said extension and saidopposite end of said shaft; and means located in said annular,unobstructed space, operatively interposed between said shaft and saidextension for resiliently limiting axial movement of said shaft uponoccurrence of abnormal axial thrust on said shaft.

14. The combination of claim 13, which further comprises an annulardriving member rot-atably borne on said extension; and central meanspassing through said extension for transmitting driving torque from saidmember to the shaft.

15. In a grinding machine, the combination,

of a, bearing; a shaft having an axial bore therethrough, rotatablyborne in said bearing and having a grinding wheel at an end thereof; athin driving spindle accommodated in said bore of said shaft,co-extensive therewith and further protruding from the end of said'shaftopposite to the first named end thereof; a tubular extension secured tosaid bearing on the side of said onposite end of the shaft, coaxiallytherewith; an annular drivingv member rotatably borne on said extension;resilient means at the end of said annular driving member remote fromsaid bearing, for supporting the "corresponding end 'of said spindlefrom and co-axially with said driving annular member, said resilientmeans providing a resilient torque transmission coupling between saiddriving annular member and said spindle; and further resilient means atthe end of said spindle adjacent to said grinding wheel, for supportingsaid spindle from said shaft and providing a resilient torquetransmission coupling between the same.

ETTORE BUGATTI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS (Othe references on following page) Number NumberNumber 16 Name Date Blood Jan. 7, 1941 Wigglesworth July 28, 1942FOREIGN PATENTS Country Date Great Britain June 25, 1915 Italy May23,1930 Germany Aug. 8, 1916 Germany Oct. 18, 1927' France Oct. w, 1938

